The physical characteristics of an aerosol determine its evolution in a medium and its collecting on surfaces and sampling systems. Therefore, the particles are mainly subject, depending on their size, to gravity, inertia or diffusion. However, when the particles are electrically charged, the electrostatic force can be prevalent and will strongly influence their behavior. For example, Cohen et al (1998) show the effect of the particles' charge on their deposition in the breathing apparatus. Their results show a deposition from 5 to 6 times greater, for 20 and 125 nm charged particles, than neutral particles of the same size. In the case of the unattached fraction of the 218Po, the electric charge will modify, on the one hand its mobility, on the other hand the deposition mechanisms. To control these parameters well, it is necessary to improve our knowledge of the electrification process of natural radioactive aerosols, in particular radon progeny.